Liquid crystal is a main material for a liquid crystal display device to implement a display function; and in normal industrial production, impurity ions in a liquid crystal layer may increase due to contamination in a carrying vessel, contamination during transportation, or excessively long time for fabricating the liquid crystal display device, and other uncontrollable factors. If there are relatively more free impurity ions in the liquid crystal layer during the display procedure, movement of the free impurity ions will directly affect a Flicker (FLK) value of the liquid crystal display device, resulting in a large FLK value, FLK value drift, or an image sticking, and other defects of the liquid crystal display device, which seriously affects a display effect of the liquid crystal display device.